[LegalizeVectorOps] Move VP_STORE legalization from LegalizeDAG to LegalizeVectorOps.

705636a1 moved reductions from
LegalizeVectorOps to LegalizeDAG, but the way it was done inadvertently
moved stores from LegalizeVectorOps to LegalizeDAG too. This was
not intended or desired.

Found when this was pulled into my downstream which has other changes
that make the distinction important.